/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.validation.beanvalidation;

import java.util.Iterator;
import java.util.Set;
import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;

import org.springframework.aop.framework.AopProxyUtils;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanInitializationException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

/**
 * Simple {@link BeanPostProcessor} that checks JSR-303 constraint annotations
 * in Spring-managed beans, throwing an initialization exception in case of
 * constraint violations right before calling the bean's init method (if any).
 *
 * @author Juergen Hoeller
 * @since 3.0
 */
public class BeanValidationPostProcessor implements BeanPostProcessor, InitializingBean {

    @Nullable
    private Validator validator;

    private boolean afterInitialization = false;


    /**
     * Set the JSR-303 Validator to delegate to for validating beans.
     * <p>Default is the default ValidatorFactory's default Validator.
     */
    public void setValidator(Validator validator) {
        this.validator = validator;
    }

    /**
     * Set the JSR-303 ValidatorFactory to delegate to for validating beans,
     * using its default Validator.
     * <p>Default is the default ValidatorFactory's default Validator.
     *
     * @see javax.validation.ValidatorFactory#getValidator()
     */
    public void setValidatorFactory(ValidatorFactory validatorFactory) {
        this.validator = validatorFactory.getValidator();
    }

    /**
     * Choose whether to perform validation after bean initialization
     * (i.e. after init methods) instead of before (which is the default).
     * <p>Default is "false" (before initialization). Switch this to "true"
     * (after initialization) if you would like to give init methods a chance
     * to populate constrained fields before they get validated.
     */
    public void setAfterInitialization(boolean afterInitialization) {
        this.afterInitialization = afterInitialization;
    }

    @Override
    public void afterPropertiesSet() {
        if (this.validator == null) {
            this.validator = Validation.buildDefaultValidatorFactory().getValidator();
        }
    }


    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        if (!this.afterInitialization) {
            doValidate(bean);
        }
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (this.afterInitialization) {
            doValidate(bean);
        }
        return bean;
    }


    /**
     * Perform validation of the given bean.
     *
     * @param bean the bean instance to validate
     * @see javax.validation.Validator#validate
     */
    protected void doValidate(Object bean) {
        Assert.state(this.validator != null, "No Validator set");
        Object objectToValidate = AopProxyUtils.getSingletonTarget(bean);
        if (objectToValidate == null) {
            objectToValidate = bean;
        }
        Set<ConstraintViolation<Object>> result = this.validator.validate(objectToValidate);

        if (!result.isEmpty()) {
            StringBuilder sb = new StringBuilder("Bean state is invalid: ");
            for (Iterator<ConstraintViolation<Object>> it = result.iterator(); it.hasNext(); ) {
                ConstraintViolation<Object> violation = it.next();
                sb.append(violation.getPropertyPath()).append(" - ").append(violation.getMessage());
                if (it.hasNext()) {
                    sb.append("; ");
                }
            }
            throw new BeanInitializationException(sb.toString());
        }
    }

}
